build a jig and use it to profile your cores rather than a planer. Sand abrasion is the most accurate form of material removal, and it puts far less stress on your cores / sidewalls than does blade removal. This is coming from personal experience, and after having to re-epoxy my sidewalls back on after the planer mutilated them over and over, i decided "what the hell" and tried the surface sander. I'm now investing in my own. it's 3000 bucks compared to a 200 dollar planer, but if you're looking to do a lot of skis... soooo nice. Just thought I'd share, because this was one of the biggest problems i ran into during my building process and the surface sander made it foolproof.
Happy building.
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